Wilkinson Microwave Anisotropy Probe DR5

Maximum Entropy Method Maps

The Maximum Entropy Method (MEM) is used to derive all-sky maps of the synchrotron, free-free, spinning dust, and thermal dust foregrounds at each of the 5 WMAP frequencies. Using the Smoothed I Maps minus the ILC map as input, representations of each of the foregrounds are fit to each pixel independently. The synchrotron, free-free and dust spectral indices are assumed to be constant over the sky. The shape of the spinning dust spectrum is also assumed constant, but the model includes a frequency scale factor for the spinning dust spectrum for pixels where the spinning dust prior is brighter than 0.1 mK. The MEM technique fits for the separate components and the frequency scaling of the spinning dust spectrum by minimizing an entropy functional using priors based on the listed templates: